American crocodile

American Crocodile
Conservation status
Vulnerable (IUCN 2.3)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Crocodilia
Family:	Crocodylidae
Subfamily:	Crocodylinae
Genus:	Crocodylus
Species:	C. acutus
Binomial name
Crocodylus acutus (Cuvier, 1807)
Terrestrial range of Crocodylus acutus (green).

The American crocodile (Crocodylus acutus) is a species of crocodilian found primarily in Central America. It is the most widespread of the four extant species of crocodiles from the Americas. Populations occur from the Atlantic and Pacific coasts of southern Mexico to South America as far as Peru and Venezuela. It also lives within many river systems on Cuba, Jamaica, and Hispaniola. Within the United States the American crocodile is only found within the southern half of Florida. In Florida, there is an estimated population of about 2000. Despite its close proximity to Hispaniola, the American crocodile is not found in Puerto Rico. The habitat of the American crocodile consists largely of coastal areas. The American crocodile is larger than some other crocodile species, with some males reaching lengths of 6.1 metres (20 ft) in Central and South America.

Physical description

An American crocodile hatchling in Colombia

Like all crocodilians, the American crocodile is a quadruped, with four short, splayed legs; a long, powerful tail; a scaly hide with rows of ossified scutes running down its back and tail.^[2] The snout is elongated and includes a strong pair of jaws. The eyes have nictitating membranes for protection along with lachrymal glands, which produce tears.

The nostrils, eyes, and ears are situated on the top of its head, so the rest of the body can be concealed underwater for surprise attacks.^[2] Camouflage also helps them prey on food. American crocodiles normally crawl on their belly, but they can also "high walk".^[3] Larger specimens can charge up to 10 miles per hour (16 km/h).^[4] They can swim at as much as 20 miles per hour (32 km/h) by moving their body and tail in a sinuous fashion, but they cannot sustain this speed.^[5]

American crocodiles are more susceptible to cold than American alligators.^[6] Unlike the American alligator which can subsist in water of 7.2 °C (45.0 °F) for some time, an American crocodile would become helpless and drown.^[2] It is thought that this intolerance to cold is the reason why American crocodiles never spread as far northward as the alligators. American crocodiles, however, have a faster growth rate than alligators, and are much more tolerant of salt water.^[2]

Unlike the Old World crocodiles which are sometimes cleared of parasites by birds, the American crocodile relies more on fish for parasite removal.^[2]

Size

Newborn hatchlings are about 22 centimetres (8.7 in) in size and about 60 grams (2 oz) in mass.^[7][8] The average adult is 4 metres (13 ft) long and weighs 382 kilograms (840 lb) in males, and 3 metres (9.8 ft) and 173 kilograms (380 lb) in females.^[9][10]

In the Tárcoles River in Costa Rica there are dozens of 5-meter and possibly even 6-meter individuals that frequent bridge crossings (where they are fed daily, which may have helped them reach such consistently large sizes) and are a popular tourist attraction. The Sirena River and the adjacent Laguna Corcovado within Corcovado National Park are also home to many 4 and 5-meter individuals (and possible 6-meter behemoths), as is the lagoon near the park entrance in Carate. In the United States adult length has been recorded as high as 4.6 metres (15 ft).^[7][11] This species is said to grow largest in the South American river basins, but even old males do not generally exceed 6 metres (20 ft).^[12][11] A skull of this species was found to measure 72.6 centimetres (28.6 in) and is estimated to have belonged to a crocodile of 6.6 metres (22 ft) in length.^[13] Large, mature males regularly weigh about 400-500 kg (880-1100 lb), with the 6 meter+ individuals surpassing 1000 kg (2,200 lb).^[14]

American crocodile prey can range in size from the insects taken by young crocodiles to cattle taken by large adults and includes birds, mammals, fish, turtles, crabs, snails, frogs, and occasionally carrion.^[10][15] Full grown adult males of this species have no natural predators and are capable of preying on virtually any animal unfortunate enough to be at the waters edge, although even at immense sizes fish still make up the vast majority of the crocodile's diet.

Range and distribution

Crocodylus acutus in La Manzanilla, Jalisco, Mexico.

C. acutus is the most widespread of the four extant species of crocodilians from the Americas.^[1] It inhabits waters such as mangrove swamps, river mouths, fresh waters, and salt lakes and can even be found at sea (hence its wide distribution on the Caribbean islands).^[2] Southern Florida, the Greater Antilles and southern Mexico to Colombia and Ecuador.^[7][15] The American crocodile is especially plentiful in Costa Rica.^[16] One of the largest documented populations of American crocodiles is in Lago Enriquillo, a landlocked, hypersaline lake in the Dominican Republic.^[10] The species has also been recorded from Jamaica.^[17]

The ancestors of the American crocodile are thought to have first colonized North America during an ice age, when sea levels were 300 feet lower than today. The crocodiles crossed the Florida Straits from Cuba, then established themselves in North America. The crocodiles were prevented from colonizing inland by the presence of alligators, so they established a niche in brackish, coastal waters.^[18]

American crocodiles in the United States cohabit with the American alligator, and are primarily found in Everglades National Park, Florida Bay, Biscayne Bay and the Florida Keys from Miami southward.^[6][8] A sizable population occurs near Homestead, Florida, at the Turkey Point Nuclear Generating Station.^[8][19][20] Some individuals wander northward to warm summer waters and have been sighted in Sarasota County and Palm Beach County.^[7]In the summer of 2008, a crocodile was captured in the surf on Isle of Palms, South Carolina.

Crocodiles require consistent tropical temperatures, hence their lack of distribution within the southern United States. They are saltwater-tolerant and have thus been capable of colonizing a multitude of islands within the Caribbean and on some coastal pacific islands as well. They co-exist with the smaller and less territorial American alligator within the Everglades National Park of southern Florida and with the very small Spectacled caiman within Central America. The only other crocodiles present within the American crocodile's range are the smaller and critically endangered Cuban Crocodile, along with the small Morelet's Crocodile in southern Mexico/Guatemala.

Systematics

Cuvier originally described the species as Crocodylus acutus in 1807.^[21] Over time, it commonly became known as the "sharp-snout alligator". In 1822, Constantine Samuel Rafinesque postulated that the species was in fact a crocodile.^[18]

The species was re-described as Crocodylus floridanus by William T. Hornaday in 1875,^[22][23] when Hornaday and C.E. Jackson were sent from Washington, D.C. to Florida in order to collect alligator hides. Upon hearing of a "big old gator" in Arch Creek at the head of Biscayne Bay, Hornaday and his companions searched for it and reported:

"In a few hours we got sight of him, out on the bank in a saw-grass wallow. He was a monster for size–a perfect whale of a saurian, gray in color—and by all the powers, he was a genuine crocodile!"^[24]

Crocodylus floridanus is now considered an invalid junior synonym of C. acutus.^[25][26]

Conservation status

Due to hide hunting, pollution, loss of habitat, and removal of adults for commercial farming, the American crocodile is endangered in parts of its range.^[8] In 1972, Venezuela banned commercial crocodile skin harvesting for a decade, as a result of 1950s and 1960s overhunting.^[27]

One thousand to two thousand American crocodiles live in Mexico and Central and South America, but populations are data deficient.^[10] The American crocodile is considered a vulnerable species, but has not been assessed since 1996.^[1] It has an estimated wild population of 500 to 1,200 in southern Florida.^[28] On March 20, 2007, the United States Fish and Wildlife Service declassified the American crocodile as an endangered species, downgrading its status to "threatened"; the reptile remains protected from illegal harassing, poaching or killing under the federal Endangered Species Act.^[29][30] While not endangered, the American Alligator is also protected in the United States so that no crocodiles are killed by mistake.

Interaction with humans

American crocodiles can be dangerous to humans, and attacks in Mexico, Costa Rica, and Guatemala are not unprecedented. These attacks rarely make international news, and therefore this species is not as well-documented a man-eater as its relatives.^[2] The species is reportedly timid, and seemingly lacks the propensity to attack humans as seriously as Old World crocodiles can.^[18] In May of 2007, there were two instances within one week of children being attacked and killed by this species—one in Mexico just south of Puerto Vallarta and one in Costa Rica.^[31][32] No attacks on humans by the American crocodile have been reported in the United States, despite assorted anecdotes.^[33]

References

External links

• American Crocodile
• American Crocodile at Crocodilian Species List
• University of Florida's crocodile research in Southwest Florida
• National Parks Conservation Association - American Crocodile
• American crocodile at the Encyclopedia of Life

Media

• Crocodylus acutus at CalPhotos
• ARKive images and movies of the American crocodile (Crocodylus acutus)